In a large ovenproof skillet or Dutch oven set over medium heat, cook the ground beef, breaking up meat with a wooden spoon, until browned through, 3 to 5 minutes. Drain the fat from the meat. Add onion, garlic, jalapeño, pinto beans, tomato sauce, and tomato and remove pan from heat. Top with cheese.

In a medium bowl, combine cornmeal, flour, egg, and buttermilk. Pour the mixture on top of the meat mixture.